Among the safety enhancements are more fencing, louder train horns and, under certain circumstances, speed restrictions of 15 mph at stations.

The recommendations were presented Thursday at a meeting of the safety and operations committee of the MTA’s board of directors. Authority officials say they want to implement all of the measures by June 2013.

“There is no question the reason for the improvements is to make the crossings safer for motorists and pedestrians,” said Vijay Khawani, MTA’s executive officer for corporate safety. “We hope the public heeds these warnings and signs when they activate.”

Although three minor accidents involving motor vehicles occurred during Expo’s trial runs, Khawani said there have been no collisions with cars or pedestrians since the line’s official opening in April.

Expo, which averages about 18,000 boardings per workday, runs 8.6 miles between downtown Los Angeles and Culver City via Exposition Boulevard. Construction of the second phase to Santa Monica is underway.

Many of the safety enhancements will be at the intersection of Exposition and Rodeo Road, where Expo trains travel at 40 mph through a maze of traffic signals, signs, crosswalks and pavement markings for bicycles. Critics have said the complex crossing could be confusing and potentially dangerous for the public.

Plans call for 14 improvements to the crossing, including barriers, additional signage for bicyclists, audible warning signals, and directions for motorists and pedestrians.

The improvements stemmed from a request by Los Angeles Mayor Antonio Villaraigosa in late May to have the MTA assess the safety of Expo’s crossings.

Villaraigosa cited the concerns of Najmedin Meshakti, an engineering professor and safety expert at USC, who had questioned the adequacy of precautions and warnings at several intersections along the line and next to the university.

The mayor “is pleased that many of these concerns have been and are currently being addressed by Metro. The safety of drivers, pedestrians and Expo line riders and employees is paramount,” a spokesman for Villaraigosa said.

The request prompted the MTA to form a task force that included the Los Angeles Department of Transportation, the Los Angeles County Sheriff’s Department and the California Public Utilities Commission, which regulates rail crossings in the state.

“This is good news to hear. Any step to improve the grade crossings is music to my ears,” said Meshkati, who added that he is still concerned about the Exposition and Rodeo intersection.